Patellofemoral disorders: anatomy, biomechanics, pathology and treatment
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This document discusses patellofemoral disorders, including their anatomy, biomechanics, pathology, and treatment. It describes the anatomy of the patella and trochlea, as well as medial and lateral stabilizers. Biomechanics discussed include joint reaction forces, contact areas and pressures. Pathologies include traumatic injuries, atraumatic causes like chondromalacia and malalignment syndromes. Treatment depends on factors like age, cartilage damage, and underlying causes; it ranges from conservative options to various surgical procedures. The take home message is that patellofemoral disorders require careful evaluation of the whole limb and conservative treatment first before considering surgery.
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Patellofemoral disorders: anatomy, biomechanics, pathology and treatment
- 1. What we should know about: Patellofemoral disorders AKRAM ALDAWOUDY, Mch.orth., FRCS
- 3. Anatomy The patella •Patella is the largest sesamoid bone •Thickest articular cartilage in the body •Up to 5mm at central ridge •Articular surface is divided into the lateral facet and the medial facet •Four different anatomical shapes probably the result of the stress imposed on it.
- 5. Anatomy The trochlea •Asymmetric medial and lateral facets, with the lateral facet little more prominent and more proximal •The greater height of the lateral facet of the trochlea and the congruence between the sulcus and the ridge are important for stability and constitutes a structural bony stabilizer.
- 7. Anatomy Medial Stabilizers • • • • • Medial retinaculum Including medial patellofemoral ligament MPFL runs from medial border of patella to adductor tubercle 75% restraining medial force Vastus Medialis obliquus Pulls at 55 to 70 degrees
- 8. Anatomy Lateral Stabilizers •Lateral retinaculum •Superficial attaches to ITB •Deep, 3 bands •Connects to IT band, tibia, & lateral epicondyle •IT band moves posteriorly in flexion •Contributes to tilt and subluxation •Vastus lateralis •Main muscle inserts proximally at angle of 31 deg •Vastus lateralis obliquus •Distinct distal portion from lateral intermuscular septum
- 10. Biomechanics •The patalla pushes away the patellar tendon from the femorotibial contact point, increasing the patellar tendon moment arm (pulley action) •Centralization of the divergent forces and transmit them in a frictionless way to the tibial tubercle •Thichest articular cartilage, highiest compressive forces
- 11. Biomechanics •Joint reaction forces, the result of the tension developing in the quadriceps and patellar tendons (multiples of body weight) •0.5 level walking •3.3 stair climbing •7.8 squats •Patellofemoral contact areas, moves proximally and broadens with increasing flexion.
- 13. Biomechanics •Patellofemoral contact pressure, ratio of patellofemoral reaction ferce to patellofemoral contact areas, most important •Patellofemoral contact pressure increases with patellar malpositioning, as patellofemoral contact areas decrease
- 14. Angle of pull of the quadriceps (Q-angle) Line drawn from ASIS to Mid-patella and Line drawn from mid-patella to tibial tubercle Normal Q angle= 15
- 15. Pathology •Traumatic: bony chondral ligamentous Merchant’s classification, sophisticated, though comprehensive •Atraumatic, Insall classification
- 16. Insall Classification •Presence of cartilage damage chondromalacia Osteoarthritis osteochondritis dissicans •Variable cartilage damage malalignement syndromes synovial plicae •Usually, normal cartilage peripatellar causes: bursitis, tendinitis Overuse syndromes Reflex sympathetic dystrophy Patellar abnormalities
- 17. Pathology •Primary OA •Pat fem maltraching
- 18. Chondral Pathology •Diagnosis •history: pain on getting to stairs and on kneeling, clicking, age, trauma • Clin. exam: patellar squeeze, tender undersurface, tend lat.retinaculum •Imaging: plain probably enough, MRI ?!!! ALWAYS LOOK FOR AN UNDERLYING FACTOR
- 20. Chondral Pathology •Treatment: still a problem, especially in young pts. Depends on: •Age of the pt., age of the knee •Generalized or localized lesions •Underlying factor, Maltraching •Stage of the disease
- 21. Chondral Pathology •Conservative management should be always tried first Rest Reduction of wt. Restriction of activities Quadriceps training NSAIDS PT
- 22. Chondral Pathology •Treatment: •Operative, DECECION CATIOUSLY TAKEN •Correction of the underlying maltraching •Lateral retinacular release, may lead to worse results ??!! •Articular cartilage management, from cell to metal
- 23. Chondral Pathology •Arthroscopic debridement/chondroplasty •Microfracture •Chondral grafts •ACI •Generally less successful than for condylar lesions •Anterior Displacing Osteotomies •Fulkerson •angled for less medialization •Maquet •avoid huge grafts
- 24. Chondral Pathology •Patellectomy Mainly of historical interest •Patellofemoral arthroplasty Generally for older, lower demand patients Not as well proven as TKA •TKA Gold standard if coexistent femoral-tibial arthritis Reasonable in older, low demand patients with severe PF and some other compartment disease
- 25. Maltraching A- Acute dislocation: •Usually presents to A&E after an injury!! Easy reduction •Often hemarthrosis •If aspiration returns fat then suspect fracture •40% risk of osteochondral injury •Many missed on Xray •MRI better •Most often medial patellar facet and lateral femur •Most often underlying alignment issues
- 28. Maltraching •Treatment of acute form: •Extend knee to reduce •If x ray changes, fat in joint, or crepitus consider scope •Physical therapy •Primary repair of MPFL only in selected pts. •50% will probably need eventual surgery •Early interveniton may increase chronic pain and arthrofibrosis
- 29. Maltraching B-The chronic form: •May present with pain and/or mechanical symptoms •Medial and lateral patellar translation Compare medial to lateral and side to side Apprehension test
- 30. Careful planning
- 31. Maltraching Consider: •Overall limb alignment, valgus knee, valgus heel, femoral anteversion… •Trochlear geometry •Patellar tilt •Quadriceps function •Age, style of life … •Beware of hyperlaxity, bilaterality •Rotational alignment of the whole limb •Degree of sublaxation •Only dynamic instability !!! •Degree of articular cartilage pathology • J-sign, pat height
- 32. Q Q
- 34. Maltraching •Radiology •Good quality x rays •Whole leg standing films •Tangential views •CT •MRI ??!!!
- 35. Maltraching Conservative treatment •Rest, Ice, NSAIDS •Physical therapy •Should be tried for several months before more aggressive measures •Avoid aggressive quad strengthening if pain important •Patellar tracking braces •Avoidance of offending activities
- 36. Maltraching Surgical treatment: tailored for every pt. indiviually •Lateral release: Probably to be done with lateral patellar compression syndrome •Distal realignment: Transfer, anterior, anteromedial, posterome dial (not done) Osteotomies, valgus knees
- 38. Maltraching •Proximal realignment: Trochleoplasty, Good results in well selected cases, open and recently !!! arthroscopic MPFL reconstruction “advancement”, commonly done now, different techniques, isolated gracilis graft or a strip of patellar tendon
- 40. Take home message •Patellofemoral joint disorders one of the very complex issues •Look at the limb as a whole •Conservative measures always come first •Surgery may be devastating if not carefully planned for •Lateral release over done ??!! •MPFL reconstruction coming to be a standard procedure